I have a .300 Whisper on a Brno Fox 2, I got it built up way before the .300 Blackout was thought about. I use mine for hunting Red deer in a noise sensitive area, I originally thought of hunting with subsonic's but gave that up as a bad joke in the end. The .300 Whisper is still pretty quiet shooting full power loads as it only burns about 17 gns of 2205 to get a 160 gn Hornady FTX to do 1,900 fps.
The maximum range I have shot any game at was a big red stag at 200 meters and it was no issue at all just one shot, all other shots to date have been at less than 150 meters, and none have run beyond 30 meters. I have shot well over a twenty or so red deer with the .300 whisper and find it more than satisfactory if the ranges are kept under 200 meters. the 160gn FTX performs very well at these ranges and modest velocities. Even though I have used the 160gn FTX Hornady's for over 10 years and I'm hugely happy with the bullet I recently bought some 140gn Hornady monolithic to try out to see if I can eek out an extra few fps's to extend the range a tad.